<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8"/>
	<title>demo1</title>
	<meta name="keywords" content=""/>
	<meta name="description" content=""/>
	<meta name="viewport" content="width=device-width"/>
	<link rel="shortcut icon" href="img/touchicon.png"/>
	<link rel="stylesheet" href=""/>
	<style type="text/css">
		#box{width:500px;margin:20px auto;}
	</style>
</head>
<body>
	<div id="box"></div>
	<script>
		var i = 100;
		var boxObj = document.getElementById('box');
		var s = '';
		while (i>0) {
			s += '<hr style="width:'+ i +'%;"/>' ;
			i -= 20;
		}
		boxObj.innerHTML = s ;
	</script>
</body>
</html>